Seal pork chunks in a bag or glass bowl along with soy sauce, garlic, ginger and oil. Let marinade for at least 30 minutes.
Meanwhile, make sweet and sour sauce. Add all the sauce ingredients into a sauce pot, except for starch and 4tbsp of water. Bring to a boil. Meanwhile, mix cornstarch and water together to be used as a thickener. Once sauce has begun to boil, add the thickener and then lower heat to simmer. Stir frequently until sauce is nice and thick and all ingredients are well combined.
Heat oil in dutch oven to 350'F.
Coat the marinated pork in the cornstarch so that the pork will be crispy after frying. Fry half of the pork in the hot oil. Then remove and fry the other half.
Last, heat a pan along with two tablespoons of the oil from the dutch oven. Then add onions and peppers. Sautee for until onions are translucent. Then add the pork and sauce. Mix well.
Serve with scallions on top.